@book { EinigeVersucheinGrundlosem,
    title = "Einige Versuche in Grundlosem",
    author = "Rolf {Lüscher}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1071136"
}